3) Lissajous raster systems used in linear accelerators typically include a resonance driver, which is operating in a high Q resonance loop. The resonance driver typically powers an air-core raster magnet with a sinusoidal current waveform. As the sinusoidal waveform approaches its peak, it slows down at the edge of the scan region in order to reverse direction. At the edges of the scan region, the scanning velocity of the electron beam becomes nearly zero. The slower scanning velocity causes much more beam energy to be deposited along the boundaries and the four corners as shown in the raster density 2D and 3D histograms of FIG. 1 and FIG. 2 respectively.
4) Eventually, as a result of the increase in deposited energy in the boundaries and four corners, overheating occurs in the target material. Experimental measurements, determined by a luminosity scan along with a magnetic spectrometer, show that the luminosity decreases gradually as a result of the increase in beam current. This indicates that a local overheating effect near the boundaries and the corners of a Lissajous raster pattern contributes an uncertainty in the target length, which leads to a negative effect on the accuracy of the experimental data.
5) With the use of the prior art Lissajous raster system as described above, employing a magnet driven by a sinusoidal current waveform, the maximum allowable beam current is limited to about 200 μA to avoid overheating of the target.
6) What is needed is a system for producing a raster pattern for a linear beam having a highly uniform raster density distribution, elimination of target heating by non-uniform raster density distributions, and higher achievable levels of beam current. What is especially desired is a linear beam raster magnet driver that is capable of producing at least 100 A of linear current swing at 25 kHz for use with high-energy accelerator facilities and in applications such as medical therapy by heavy ion, cancer treatment by electron accelerators, ion implantation for semiconductor chip production, and modification of material behavior in material science.